Merge remote-tracking branch 'upstream/master' into pipeline-notifications

* upstream/master: (33 commits)
  removes extra line for empty milestone description
  code formatting corrected
  Fix status code expectation
  Stop clearing the database cache on rake cache:clear
  Fix error in generating labels
  Fix bug where e-mails were not being sent out via Sidekiq
  Document link syntax introduced by !5586
  Fix documents and comments on Build API `scope`. #23146 #19131
  adds entry in CHANGELOG
  removes extra line for empty issue description
  Re-organize queues to use for Sidekiq
  Fix wrong endpoint in api/users documentation, fix same typo in spec describe blocks
  Update CHANGELOG
  Fix object data to be sent to fetch analytics data
  Fixed compare ellipsis messing with layout
  Change "Group#web_url" to return "/groups/twitter" rather than "/twitter".
  Fix broken label uniqueness label migration
  Fix project member access levels
  fix font weight of project feature settings
  Add hover to trash icon in notes
  ...

2 files changed, 40 insertions, 1 deletions

diff --git a/doc/development/README.md b/doc/development/README.md
index 9706cb1de7f..fb6a8a5b095 100644
--- a/doc/development/README.md
+++ b/doc/development/README.md
@@ -14,7 +14,8 @@
 - [Testing standards and style guidelines](testing.md)
 - [UI guide](ui_guide.md) for building GitLab with existing CSS styles and elements
 - [Frontend guidelines](frontend.md)
-- [SQL guidelines](sql.md) for SQL guidelines
+- [SQL guidelines](sql.md) for working with SQL queries
+- [Sidekiq guidelines](sidekiq_style_guide.md) for working with Sidekiq workers
 
 ## Process
 
diff --git a/doc/development/sidekiq_style_guide.md b/doc/development/sidekiq_style_guide.md
new file mode 100644
index 00000000000..e3a20f29a09
--- /dev/null
+++ b/doc/development/sidekiq_style_guide.md
@@ -0,0 +1,38 @@
+# Sidekiq Style Guide
+
+This document outlines various guidelines that should be followed when adding or
+modifying Sidekiq workers.
+
+## Default Queue
+
+Use of the "default" queue is not allowed. Every worker should use a queue that
+matches the worker's purpose the closest. For example, workers that are to be
+executed periodically should use the "cronjob" queue.
+
+A list of all available queues can be found in `config/sidekiq_queues.yml`.
+
+## Dedicated Queues
+
+Most workers should use their own queue. To ease this process a worker can
+include the `DedicatedSidekiqQueue` concern as follows:
+
+```ruby
+class ProcessSomethingWorker
+  include Sidekiq::Worker
+  include DedicatedSidekiqQueue
+end
+```
+
+This will set the queue name based on the class' name, minus the `Worker`
+suffix. In the above example this would lead to the queue being
+`process_something`.
+
+In some cases multiple workers do use the same queue. For example, the various
+workers for updating CI pipelines all use the `pipeline` queue. Adding workers
+to existing queues should be done with care, as adding more workers can lead to
+slow jobs blocking work (even for different jobs) on the shared queue.
+
+## Tests
+
+Each Sidekiq worker must be tested using RSpec, just like any other class. These
+tests should be placed in `spec/workers`.